Production of butadiene



April 23, 1946. T. H. MANNINEN PRODUCTION OF BUTADIENE Filed Nov. 4, 1944 um... .S

760mm' ff nahmen W2k Fr INVENTOR BY @W r M Y ATTORNEYS Patented Apr. 23, 194,6,

y APRODUCTION F BUTADIENE Thomas H. Mannlnen,'Stamford, Conn., assignor to U. S. Industrial Chemicals, Inc., New York, N. Y., a corporation of Delaware Application November 4, 1944 Serial No. 561,961

7 Claims.

This invention relates to the production of 1,3-butadiene from 1,3-butylene glycol and particularly to an improved method whereby dehy,

dration of the glycol is eiected economically and in a manner permitting commercial recovery of the desired product.

Most of the earlier suggestions, concerning the dehydration of 1,3-butylene glycol involve treatment of the glycol in the vapor phase with the aid of a suitable catalyst. These procedures result iin excessive decomposition and cloggingof the catalyst which must be revivied frequently by burning in oxygen or air to remove carbon therefrom. 1 Such methods are grossly inefficient and commercially impracticable, particularly with respect to the reduction of activity of the catalyst due to carbonization and the necessary repeated burning of the catalyst with resulting loss of activity.

It is the object of the present invention to prepare 1,3butadiene from 1,3-butylene glycol ina Ysimple| economical and efficient procedure suitable for commercial application.

Another object of the invention is the provision of a method which assures prolonged activity of the catalyst with provision for renewal of the catalyst without interrupting the procedure.

Other objects and advantages of the invention will be apparent as it is better understood by reference to the following specification yand the accompanying drawing, which illustrates diagrammatically an apparatus suitable for the practice of the invention.

I have discovered that butadiene can be pro. duced advantageously by introducing 1,3-butylene glycol in relatively low concentrations into a covered and returned to the body of inert liquid for further conversion. l

The' temperature to which the. inert liquid is heated will depend somewhat upon the activity of the catalyst, the rate of feed and the kind of liquid used. Temperatures between 220 and 350 C. are most favorable for the reaction, and I prefer to conduct it within the range of 260 to 285 C. If the temperature is as low as 200 C., the reaction becomes too slow for practical commercial operation. If it is permitted to exceed 350 C., there is a tendency toward undesired side and decomposition reactions.

Many different types of liquids may be utilized in the procedure to conduct the glycol through the heating zone. In general', the characteristics of such a liquid should be that it is inert under the conditions of operation, that is that the liquid does not decompose and does not react with the butylene glycol, butadiene or any other products of the reaction or the catalyst employed during the dehydration of the 1,3-butylene glycol. The liquid should not have a boiling point below that of the reaction temperature, although such a liquid may be used, provided the reaction is conducted under pressure. The liquid should be selected from inert organic liquids having the desired characteristics.

It is not necessary that the inert liquid and the butylene glycol should be completely miscible.

As already indicated, the temperature to which the inert liquid is raisedV in thelheating zone and the rate of feed of butylene glycol are adjusted so that there is lno accumulation of butylene body of inert liquid which is circulated continuously in heat exchanging relation with a heating medium which raises the temperature of the liquid to the desired point. As the inert liquid is circulated, it is continuously withdrawn from the heating zone and the vapor including the butadiene is separated so that the inert liquid can .be returned for furtherY additions of the glycol and recirculated through theheating zone. The inert liquid includes a dehydration catalyst which may be dissolved or suspended therein. The glycol is introduced at such a rate as to malntain a low concentration thereof in the circulating inert liquid. T he butadiene formed, being gaseous at the temperature of the reaction, is withdrawn continuously with other vapors .rising from the body of liquid and is subsequently separated from such vapors. The latter may contain butenol or partially converted glycol which is reglycol in the inert liquid during the operation, the glycol being converted continuously into butadiene with some relatively small proportion of butenol. It is believed that slight solubility of the butylene glycol in the inert liquid, of'the Iorder of 1% or less, is favorable to the reaction,

but in this respect I do not wish to be restricted to any particular theory.

Among the linert organic liquids which are suitable for use in the procedure, are diphenyl ethane, hexaethyl benzene, benzyl ether, a mixture of diphenyl and diphenyl oxide known as Dowtherm, a refined petroleum product known as NujoL Texas Co. #531 wash oil, a topped fuel oil having a boiling point of 260-270 C., Bunker C oil and a higher alcohol known to the trade as cyclic Cm alcohol. It will be observed that the chemical composition of the inert liquid may vary markedly. The essential characteristics have been indicated. Undoubtedly `a considerable number of additional organic liquids having simto temperatures such as those employed in the V procedure. Such decomposition products, are phosphates, but the precise composition of the salt or salts in the inert liquid at the temperature maintained cannot be determined accurately. Any of the phosphates mentioned or the resulting phosphate compounds in the inert liquid are active catalysts for the reaction.

The catalyst may be introduced to the inert liquid as such, but I prefer to mount it on a suitable iinely divided support such as carbon, "Filtercel, Celite, kaolin or clays and thelike. The supported catalyst may be prepared in any of the well known ways, for example by evaporatween 220" and 350 C., or more Vpreferably between 2-60 and 285 C., by means of a boiler (not shown). In passing through-the tubes Ii, the

inert liquidincluding the catalyst and the glycol v'as required through a pipe iB'controlled by a tion to dryness of an aqueous solution of the phosphate in contact with the nely divided supporting material while the solutionis stirred to ensure uniform impregnation of the support. For example, 6 parts by weight of di-ammonium phosphate are dissolved in about 50 parts of water and added to 12 parts of Filtercel The mass is evaporated to dryness with continuous stirring.

The use of a mounted catalyst in general resuits in more efficient operation, avoiding the possibility that the catalyst may coalesce into masses, althbugh in the present procedure the continuous and active agitation resulting from circulation reduces`such a possibility to the minimum. While ammonium phosphate is preferred as a catalyst for the reaction, various other catalysts are available and can be used. Among them are phosphoric acid, toluene suiphonic acid, ammonium sulphate, a mixture of calcium and ammonium phosphates, aniline phosphate, acid sodium phosphate, kaolin and clays such as Attapulgus clay. These catalysts may be used as such or mounted on supports as in the case of ammonium phosphate.

liquid. If, however, the catalyst is finely divided;

an amount of 2% by weight of the liquid or even less is required to ensure adequate activity. yThe neness of the catalyst and the proportion thereof can be varied Within wide limits to secure the desired result;

The procedure will be readily understood by reference to the drawing, it being understood that the apparatus described is merely illustrative of suitable equipment for the purpose. A relatively small chamber 5, adapted to receive the inert liquid including the catalyst and the glycol as fed thereto, encloses an immersion pump 6 which is adapted to be driven by a motor 1 mounted on the chamber through a shaft 8` The pump 6 forces the inert liquid, including the catalyst and valve i 3 and delivered to the extension i1 through a pipe 20. The glycol is thus mingled with the inert liquid including the catalyst which is recirculated through the heating zone to eiect conversion. Additional 'inert liquid including 'the catalyst may be introduced through a pipe 2| controlled by a valve 22 to make up anyincidental losses. When the catalyst is exhausted, the liquid containing it may be withdrawn from the chamber 5 through a pipe 23 controlled by a valve 24, and fresh liquid with the catalyst therein may be introduced through the pipe 2|. Thus, the procedure may be -maintained `in substantially continuous operation. p

The vapor from the separator I6 rises through apipe 25 to a condenser 26 which is maintained at a suitable temperature by circulation of liquid such as water through the pipes 21 and 28 to condense any vapors from the inert liquid and un- `reacted glycol. The condensate returns through a pipe 29 to the separator I6 and thence to the chamber 5.

The uncondensed vapors leave lthe condenser 2E through a pipe 30 and are delivered to a condenser SI whichis cooled by water or other liquid circulated through pipes 32 and 33, to condense the vapor other than the butadiene. The latter is withdrawn through a pipe 34. It may be deiivered in the vapor phase to any suitable receptacle, but preferably is compressed by a compressor 35 to a suitable pressure and subjected -to cooling at that pressure` in a condenser 36 maintained at the desired temperature by Water or other liquid circulating through the pipes 31 and 38. The liquid butadiene is Withdrawn through a pipe 39 and valve 39 and delivered tosuitable storage facilities. The condensate from the condenser 3l is delivered to a separator 40 having a sight glass 4 I. It separates into an oily layer and a water layer. The oily upper layer,

the glycol, through a pipe 9 to the heating chamconsisting substantially of butenol, is Withdrawn through a pipe 42 and delivered to the extension i1 where it mingles with the fresh glycol and with the inert liquid including the catalyst so that it may be subjected to further reaction.

The lower watery layer, which contains some butenol, is withdrawn through a pipe 43 controlled by a valve 44 and is delivered to a fractionating column i5 having a plurality of trays 46 with the usual bubble caps 41. A heating coil 48 is disposed at the bottom of the column 45 and adapted to be suppliedl with steam orother heating medium. By fractionation the liquid supplied through the pipe 43 is separated'into water which is withdrawn from the bottom of the column through a pipe 49, and vapor consisting of an azeotrope of butenol and Water which is delivered from the top of the column through a pipe 50. The vapor passes through a condenser 5I cooled by Water or other suitable liquid circulating through the pipes 52 and 53. The condensate isdelivered through a pipe 54 to the pipe 20 and thus returns for recirculation with the inert. liq- A mixture of diphenyl ethane and nely divided ammonium phosphate in the ratio by weight of 25 to 1 is placed in the chamber S-a'nd circulated through the heating zone. 1,3-butylene glycol is introduced at the rate of W4 part by weight per hour. The temperature of the circulating liquid is raised to 255275 C. Thebutadiene formed is separated and recovered as, hereinbefore described. Three-quarters of the input butyleneglycol is converted to butadiene and the-gas produced averages 95% butadiene.' 'When th rate of feed of butylene glycol is increased to 11/3 parts by weight per h our'the conversion and purity of butadiene is substantially the same.

l Example II A mixture consisting of 250 parts of Texas Co.

#531 wash oil and 6 parts of aniline phosphate prepared by mixing aniline and. phosphoric acid in the ratio of two mols of aniline to 1 mol of ortho phosphoric acid are circulated with a butylene glycol feed of 9 parts per hour. Gas is produced having a butadiene content of 92% and the conversion of glycol to butadiene was substantially the same as in Example I.

Example 111 A suspension of 1 part of catalyst composed of diammonium phosphate mounted on Filtercel in about 30 parts of Texas Co. #531 wash oil is circulated and glycol fed thereto at the same rate as in Example II. Butadiene is produced in a yield of 89% with a gas purity of 95%.

The foregoing examples are merely illustrative of the various modifications which can be made in the operation of the invention. Success in the procedure does not depend upon the selection of a specic inert liquid or upon the use of a specic catalyst. The important criteria of the invention are the circulation of a relatively small body ofthe inert organic liquid including the catalyst and the glycol through a heatingA zone in which the liquid is raised to the necessary reaction temperature and after which the vapor including the butadiene is separated while the liquid is returned for further circulation. Any dehydration catalyst which will maintain its activity under the conditions of the reaction may be used. The invention is limited, therefore, only with respect to the essential conditions` of operation as hereinbefore 'set forth.

The particular advantages of the invention reside in the fact that only a relatively small body of the inert organic liquid and a proportionally small amount of catalyst in required. Heat transfer to this relatively small body of liquid is materially simplied. The time during which the liquid remains in the heating zone is limited. Hence the formation of polymers and other undesirable products of side reactions is reduced to the minimum. AMoreover the rate of ilow of such reactions. The relatively smally immersion pump can be used under the conditions specified without danger of mechanical breakdowns or other factors which might adversely aiect the operation.

Various changes may be made in the apparatus i employed and in the details of procedure without departing from the invention or sacrificing the advantages thereof.

I claim:

1. The method of producing 1,3-butadiene by dehydration of 1.3-butylene glycol which comprises circulating a body of inert'organic liquid including a dehydrating catalyst through and in heat-exchange relation with a heating medium whereby the temperature of the inert organic liquid is maintained between 220 and 350 C., feeding the glycol continuously to the inert organicliquid before it is subjected to heat exchange relation with the heating medium, withdrawing vapor from the inertorganic liquid after the heat exchange, separating butadiene from the vapor and returning the inert organic liquid for recirculation `with the continuously fed glycol.

2; The method of Producing 1,3-butadiene by dehydration of 1,3-butylene glycol which comfprises circulating a body of inert organic liquid including a dehydrating catalyst through and in heat exchange relation with a heating medium whereby the temperature of the inert organic liquid is maintained between 220 and 350 C., feeding the glycol continuously to the inert organic liquid before it is subjected to heat exchange relation with the heating medium, withdrawing vapor from the inert organic liquid after the heat exchange, condensing the vapor, separating butadiene from the condensate and returning the inert organic liquid and a portion of the condensate for recirculation with the continuously fed glycol.

3. The method of producing 1,3-butadiene by dehydrationof 1,3-butylene glycol which comprises circulating a body of inert organic liquid including a dehydrating catalyst through and in heat exchange relation with a heating medium whereby the temperature of the inert organic liquid is maintained between 220 and 350 C., feeding the glycol continuously to the inert organic 'liquid before it is subjected to heat exchange relation with the heating medium, withdrawing vapor from the inert organic liquid after the heat exchange, condensing the vapor, sepa rating butadiene from the condensate, separating the condensate into oily and watery layers, removing water from-the watery layer and returning the oily layer and the residue freed from the liquid through the heating chamber can be water with the inert organic liquid for recirculation with the continuously fed glycol. ,I

4.. The method of producing 1,3-butadiene by dehydration of 1,3-butylene glycol which comprises circulating a body of inert organic liquid with'a dehydration catalyst suspended therein through and in heat exchange relation with a heating medium whereby the temperature of the inert organic liquid is maintained between 220 and350 C., feeding the gycol continuously to the inert organic liquid before it is subjected to heat exchange relation with the heating medium, withdrawing vapor from the inert organic liquid after the heat exchange. separating butadiene from the'vapor and returning the inert organic liquid for recirculation with the continuouslyfed glycol.

5. The method of producing 1,3-butadiene by dehydration of 1,3-butylene glycol which coinprises circulating a body of inert organic liquid with a dehydration catalyst supported on a carrier suspended therein through and in heat exchange relation with a heating medium whereby the temperature of the inert organic liquid is maintained between 220 and 350 C., feeding the glycol continuously to the inert organic liquid before it is subjected to heat exchange relation with the heating medium. withdrawingy vapor from the inert organic liquid after the heat ex'- change. separating butadiene from the vapor and returning the inert organic liquid for recirculation with the continuously fed glycol. l

- 6. The method ci' producing 1,3-butadiene by dehydration oi' Al-butylene glycol which comprises circulatinga body of inert organicy liquid' including a dehydrating catalyst through and in `heat exchange relation with a heating medium whereby the temperature of the inert organic liquid. is maintained between 260 and 2859 C.,

feeding the glycol continuously to the inert organic liquid before it is vsubjected to heat exwhereby the temperature of the inert organic liquid is maintained between 260 and 285 C.. feeding the glycol continuously tonthe inert organic liquid before it is subjected to -heat ex@ change relation with the' heating medium, withdrawing vapor from the inert organic liquid after the heat exchange, condensing the vapor. separating butadiene from the condensate and returning the inert organic liquid and a portion o! the condensate for recirculation with the continuously ted glycol.

THOMAS H. MANNINEN. 

